The present invention generally relates to box fabrication, and particularly relates to a sheet feeding apparatus for box fabrication.
A common type of box forming apparatus folds flat sheets of material, such as corrugated cardboard, to form box corners. The folding process brings the outside edges of the starting sheet into overlapped alignment, thereby forming a seam that is glued or taped by the apparatus.
Finished box sizes obviously depend on the starting sheet dimensions, and several factors in practice limit sheet size. For example, the sheets, also referred to as “blanks,” generally include slots or other cuts corresponding to the top and bottom flaps of the finished box, for example, and the size of blank cutting dies may be limited. Further, the maximum size of preprinted sheets may be limited by printing process capabilities. In theory, one could use a printing apparatus of whatever size was needed for the desired finished box dimensions. Simple economics weigh against this approach, however, because large sheet printers often carry high price premiums.
A more practical approach to forming larger boxes uses two sheets, which are folded together to form a single finished box. The sheet pairs can be individually cut and printed, thereby allowing relatively large finished boxes, while effectively halving the working width requirements of the sheet cutters and printers used to process the sheets in advance of box formation.
While the two-piece approach to large box formation offers upstream cutting and printing advantages, it does complicate the actual folding and gluing operations. For example, proper box formation relies on carefully aligned feeding of the sheet pairs. Further, the two-piece approach involves more complicated seam formation and alignment operations, because two seams are involved, rather than one.
These complications can place significant burdens on machine operators. For example, machine operators may be required to manually overlap and align the sheets in a sheet pair before feeding them into the folding/gluing apparatus. While this manual processing may reduce the required complexity of the folder/gluer apparatus, it requires significant sheet handling by operators and significantly reduces box production as compared to fully automated feeding, folding, and gluing. Some forms of automatic feeding of sheet pairs are known, but these known approaches require potentially large and/or complex feed paths.